Sal Suds or Castile Soap – Which One Should You Use?

I talk a lot about the exceeding versatility of Dr. Bronner’s Castile Soap and Dr. Bronner’s Sal Suds.  There are so many overlapping uses.  But is there any time in which they aren’t interchangeable?  Yes, but just a few.

Castile soap is primarily designed for the body.  The blend of oils (coconut, olive, palm, jojoba, and hemp) are designed to be the most nourishing to our skin.  But wait, there’s more.  Because it is such a beautifully simple soap, it also cleans many other things amazingly well, whether it’s your dog, your sinks, or your floors. You can find details of all these uses on this cheat sheet.

Because Castile soap is a true soap, it reacts with the minerals contained in hard water. (Here’s my test to find out if you have hard water.)  The more dissolved minerals there are, the “harder” the water.  The reaction of soap with these minerals in the water leaves behind an insoluble film that’s commonly called “soap scum”.  This term is a bit of a misnomer, because it’s not actually soap that remains, but a precipitate of minerals.

You’ll only notice this on shiny objects that are left to air dry.  They will take on a whitish film. (Read my post on eliminating soap scum.) Also, absorbent fabrics like towels and cloth diapers will become stiff and lose their absorbency. (But laundry in hard water is still doable – Read more here.)

Enter Sal Suds.  This is our biodegradable household cleaner developed by my dad. Sal Suds doesn’t react with hard water.  It rinses cleanly and leave surfaces sparkling. No more film on the tub or towels!

That’s all well and good, but I haven’t answered that initial question of what to use when.

Situations where I exclusively use Castile:

  • Myself – Head to toe.
  • My animals – Any Castile soap scent on my dog. Baby Unscented on my cat.
  • Pest Control – Only Castile soap has this ability to eliminate insects.

Situations where I exclusively use Sal Suds:

  • Dishes
  • Cars
  • Most Laundry – sometimes, as with bedding, I use Castile soap.

Other than these few cases, I reach for whichever is closer at hand.

Now you know what to use, but perhaps you want to know why?

Soap and detergent are both surfactants.  The word “surfactant” is a portmanteau of “Surface Active Agent.”  If you’ve ever done a belly flop into a pool, then you’ve felt the power of surface tension. Surfactants break through the surface tension of water and make water really soak in.

My brother Mike says that:

Surfactants make water wetter.

The second magical power of surfactants is that they make oil and water coexist.  Which they don’t otherwise like to do.  This is why you can’t just rinse oil off your hands.  The water runs over the oil like it’s just not there.  And it just doesn’t care.

Now brace yourselves – you’re about to learn some Greek!

Surfactants solve the oil/water repulsion because one end of each surfactant molecule is hydrophilic and the other end is hydrophobic.

Hydrophilic literally means “water (hydro) loving (philic).”  This end of the surfactant molecule grabs hold of water.  On the other side, hydrophobic means “water (hydro) fearing (phobic).”  A little exaggerated perhaps, but this end grabs the oil.

But we’re not talking about just one.  Surfactant molecules work in groups.  In a solution, they float around looking for oil molecules and snag with those hydrophobic tails, totally surrounding each oil molecule so there’s no part of the oil molecule left exposed to water.  This little nugget is called a micelle.

The outside of this micelle is now entirely hydrophilic, which means instant attraction to the passing rinse water which carries it all away.

It’s like they’re filling those oil molecules with a whole lotta love and reaching out and connecting them with their former enemy, those water molecules.  And once they’re connected, they realize it’s not so bad.  They can get along. They can hang out together.  I think there’s a larger lesson here.

You still with me?

So they’re both surfactants.  Now for some differences.

Soap is close to nature, made by a beautifully efficient one-step reaction of combining oil (coconut, palm, olive, jojoba, and hemp for our Castile) with a strong alkali such as sodium or potassium hydroxide (the first also known as lye).  Out of this combo, you get soap, glycerin and water. Bam!  No leftovers. No waste. Beautiful.

Detergents are more complex and must be synthesized.  They were developed during the World Wars when the oils needed for soap were scarce.  They can start with botanical substances (such as coconut oil for our Sal Suds) or with petroleum derivatives. And the uses of detergents is vast and wide.

Tidy as it would be, I can’t sum it all up by saying, “Soap good. Detergent bad.”  That would be a gross oversimplification.  There are bad soaps (not ours, of course) that are poorly made with bits of unreacted alkali floating around in them ready to saponify your very body.  You become walking bar of soap.  Ouch!

And there are excellent detergents, such as our Sal Suds, which is super duper tough on grease and completely clean rinsing, yet mild and biodegradable.

So that’s a little bit more about the magic of cleaning and the beauty of chemistry.

44 thoughts on “Sal Suds or Castile Soap – Which One Should You Use?

  1. May I reproduce all or part of this article for our newsletter or to use on-line for our store. We have been selling Dr
    Bronner’s for years. Thanks in advance.

    • Hi Phil – Definitely! Please reference the source. Thank you!

  2. Good Morning,

    First, thanks for all your information. You’ve been making my life simpler. I have a question about using Sal Suds in the laundry. I use one tablespoon for a full load of t-shirts, which seems to be enough because the wash comes out clean, then they are hung up to dry so they’ll last longer. However, the shirts that are like a sportswear fabric to wick sweat will dry with streaks of white or dots that look like they are spaced like the washer holes. This doesn’t happen to the non-sportswear shirts. I can remove them with water, but it’s an extra step. Any idea as to the cause and is there something I can do about it? I’ve tried adding Sal Suds after there is water in the washer tub, but that doesn’t take care of it. Thanks.

    • Hi Rita – I recommend adding vinegar to the rinse water. You can do this by adding it to the fabric softener compartment at the beginning. The washer won’t release it until the rinse cycle. This will help eliminate any suds that might be left on the fabrics. A second rinse cycle is another option, but I agree that the fewer steps, the better.

  3. We have a gray water system for irrigating plants; we use Sal Suds and one other cleanser for washing clothes and general cleaning. I actually used a solution of water and Sal Suds to quickly expel ants when they invade our house as they did recently during the time we experienced a mild episode of the raining down of ash from Nap and Sonoma. We’re great fans of these products and have been for several decades.

    • It’s great to hear of your experience with our products in gray water systems. That is on my list of things to research. And great tip on the ants, too! I’m glad to hear that you are safe from the fires. The ash clouds have been extremely widespread.

  4. Thank you so much for this information. That helps me to know when to use these products. There is one more thing that I would like for you to explain in another “blog” sometime. What happens when a water softening agent is used with the castile soaps? Thanks.

    • Hi Jalene – I will look into your question. I don’t know the answer off the top of my head. Is there a specific water softening agent that you are thinking of?

  5. Thank you for explaining something I’ve wanted to know and understand for about fifty years!!!

  6. How about summing up the uses for both on a new “Cheat Sheet”, similar to the Castile Cheat Sheet, but listing both products?

    • Hi Janice – This is a great idea. I will look into this!

    • Hi Tammie – I use Sal Suds much more than Castile for a couple reasons – I have hard water and with SAl Suds I don’t need the extra step of adding vinegar to the rinse water. Sal Suds is slightly more effective at stain removal and with three kids, I have lots of those. Sal Suds is even more concentrated than the Castile soap and so I need half the amount or less. Here’s a more recent post on laundry: http://www.lisabronner.com/pretreating-laundry-stains-with-dr-bronners/

  7. I have two questions.
    Is there a version of Sal Suds that is completely scent free? I would love one.
    I have a washer that requires HE detergent. Can I use Sal Suds in the machine, and if so how much?
    Thank you!

    • Hi Wendy – We only have the one formulation of Sal Suds, and it does contain fir needle oil and spruce leaf oil which adds a scent. It works well in HE machines. Just add 1 Tbsp. of the Suds.

  8. Thank you for your explaining the scum and haze we’ve noticed on our bathroom fixtures, now that we’ve moved from a house without soft water to one with hard water. Do you have also an explanation for the yellow tint we get on fiberglass (plastic) surfaces, such as our laundry sink and shower base? Is it the coconut oil?

    Thank you,

    Steve.

    • Hi Steve – I think the yellow tint is also soap scum. The coconut oil is completely saponified (turned into soap), so it is not a residue. Use the tips in the Scum, Scum Go Away post to treat it.

  9. Love Sals Soap! Have not been able to purchase for quite awhile,every time I visit your site Sals is out of stock. Primarily use as a floor cleaner, alltypes of surfaces. Devotee of Castile in the shower,told a fair skinned friend how peppermint soap got rind of a sun caused lesion on my cheek,and he’s been using ever since. As I like to say, Dr Bs cures cancer.

    • Hi Al – We did have a shortfall for a while as demand for Sal Suds exceeded our expectations, but we’re fully stocked now! I guess the word has been getting out, thanks to customers like yourself! The 32 oz. are even 15% off on our website this month (free shipping at $35), so stock up! While curing cancer might be beyond us, our products can definitely make life healthier and happier!

  10. Hi Lisa, I’m a chemist and a tech writer. I pretty much knew all these facts but still found your article an enjoyable read.

    The one on washing bedding with soap instead of detergent is also great.

    Two suggestions for the future are: real soap vs. antibacterial detergent (like most liquid ‘hand soaps’) and the results of using different alkalis in soap-making.

    • Hi Mary – Fantastic! I very much appreciate input from experts such as yourself. We are thinking along the same lines and I have a post coming soon called, “The Antibacterial Debate”. I briefly touch on the differences in alkalis in explaining the difference between our Bar and Liquid Castiles. I welcome any further elaboration you can provide.

  11. Peace and love, started reading dr bronners labels at age 19, i am now 65, still using it and depend on it. My questionis in regards to using mint fragrance to repel mice. I use peppermint soap but its a bit pricey for whole house cleaning and deoderizing. What is the most economical way to use this product and maintain that wonderful mint aroma and repel mice. Do you have any ideas.
    Thanks and God bless you, Jewette Noor Doumbia
    P.S. your fathers words helped guide me in my quest to find God and truth.

    • Hi Jewette – I am so glad our products and my grandfather’s words have been such a blessing to you. You can make a very economical housecleaning spray from our Peppermint Castile by diluting 1/4 c. of soap in 1 qt. of water in a spray bottle. You could even buy an a small bottle of pure Peppermint Essential oil and add about 10 drops to the spray bottle to increase that lovely minty smell.

  12. I’ve been using your peppermint Castile soap to clean my bath tub and toilet for YEARS!! Works great!

  13. Thank you Lisa for sharing. I’ve learned. I’ve been a Dr. Bronner product user for over a decade. I use Sals suds for the car and the peppermint soap in the bathroom…. Though haven’t used Sals for the laundry. Now I will. More over….im so glad you have kept your company and haven’t sold out.
    Your dad would be proud.
    K

    • Hi Ken – Thank you so very much for your kind words. It is an honor and a pleasure to continue my family’s legacy.

    • Hi Carla – While the ingredients in Sal Suds are much less harsh than what you find in many a conventional body cleanser, it is the Castile soap that should be your shower buddy. 🙂

  14. First, I’d like to say that I love Dr. Bronner’s products! Second, I’d like to ask, is it really necessary to use palm oil in your products? Much of the destruction of rain forests is for the planting of palm oil trees, which is not really healthy for our habitat.

    • Hi Rich – I am very glad you have brought up this important issue. The irresponsible production of palm oil has been truly decimating to animal habitat and the environment. We share your concern. The vast majority of palm oil used in food and body care products is sourced from southeast Asia with devastating results. I am happy to say that there are ways to produce palm oil that do not have this impact. In searching for options, we partnered with small scale farmers in Ghana and founded Serendipalm, a sister companies, that is producing palm oil in a way that promotes health not only to the environment and farmers but also to the communities around it. Please read more about it here: https://www.drbronner.com/about/our-suppliers/projects-and-partnerships/#about-palm-oil

      And here’s a video of our work in Ghana Sustainable Palm Oil: The Difference Fair Trade Makes.

    • Thank you Lisa for your response. I read about Serendipalm and watched the video. It does seem that you acquire palm oil from a sustainable source. Good to know!

  15. I would LOVE to use Sal Suds on my laundry, etc., etc., but I cannot tolerate any strong scents. I know you only have the scented version available, but if you ever offer an unscented option I will be “All In”!

    • The scent in the Sal Suds is much milder than what you find in our scented Castile Soaps. We will definitely get the word out to you if we release a fully unscented Sal Suds!

  16. Which one should I use to wash my baby’s clothes? I was gonna buy the Castile soap BabynUnscented but now I’m thinking I should do the Sal Suds instead? Please help this new momma to be. Thank you.

    • Hi Andrea – Congratulations! I found that baby related stains were no joke. Whether it was poop or spit up or baby food, wow, there’s a lot of things that stain. Because of this, I suggest the Sal Suds. It is slightly better at tackling those stains. You can even apply it straight on the stain. And if you opt to go the cloth diaper route, it is exceptional at cleaning those, too. One more tip: I highly recommend our Unscented Magic Balm for baby skin. It works great to prevent diaper rash, or on those little angry red lines they get in their chubby creases and it helps alleviate baby eczema. Let me know if any other questions arise!

  17. I use Sal’s Suds for dishes and housecleaning tasks, and I use the castile soaps in the shower. Both are great products which have proved their mettle. However, I’m even more impressed and grateful for your steady commitment to sustainability and supporting our ecosystem. Your recent investment in extensive solar panels and sustainable landscaping at your production facility is stunning, and an undeniable working blueprint for commercial properties everywhere. You’re again transcending the role of public advocacy, and personally investing (and building) to make the changes real and observable. This delivers not only the inspiration so needed by others, but the undeniable results over time that so many will depend on before becoming brave enough to follow suit. Change can actually occur when people like you step out first lead the way. Bravo!

    • Hi Grady – Wow! I’m bowled over by your kind words! I’m so glad to hear that you are in sync with all that we’re doing at Dr. Bronner’s. If we all do what we can, where we are, however big or small, we will indeed change the world.

  18. I have been a Dr. Bronner’s disciple for decades! They are the only products I use in my home. About 2 yrs ago, I was introduced to magnets for the clothes washer and how they enable water to penetrate fabrics, much like Sal Suds. I know use both and are very happy with the results. I learned about the magnets on Water Liberty.

  19. Just enjoyed reading this post and all the great comments! I just used Sal Suds on a RED WINE stain on one of my dinning room cushions. The stain was dried. I put a dash of Sal Suds on an old toolbrush and gently rubbed it until the stain disappeared in a matter of minutes. Then, removed residue with a cloth. Love it! I just sent you pictures before and after. I am seriously enjoying Sal Suds and just love the fact that is so natural! Thanks.

    • Thanks so much for sharing here, Margarita! And I’m glad your cushion was saved by Sal Suds!

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